1. Technical Field of the Invention
This invention relates to nonfuming, cleansing and solder fusing fluids. In soldering processes, such as those used in the manufacture of printed circuit boards, fusing fluids are used to melt and/or remelt the solder at the comparatively high temperatures used during the process. In certain processes, such as infra-red solder reflow processes, the fusing fluids also function as protective coverings for the metal surfaces. This is important, because during such processes, through handling, air exposure, etc., the electrically conductive metals present on the semicompleted circuit boards may become contaminated due to corrosion, etc. If the contaminants are not removed, their presence can lead to excess conductivity between metal strips (e.g., across intended insulators) in poor circuit board appearance and in poor adhesion of the solder.
Past results have not been entirely satisfactory, particularly when it is desired to use the fusing fluid as a protective medium to prevent contamination of the electrically conductive metal in the circuit board during the manufacturing process.
It has been discovered, in accordance with the present invention, that the foregoing and related problems can be overcome through the provision of a cleansing solder fusing fluid containing a cleansing amount of a high temperature stable primary amine or an ethoxylate thereof.
2. Prior Art
It is known to utilize amines such as ethylene diamine, monoethanolamine, diethanolamine, triethanolamine, and equivalent low molecular weight amines in the formulation of solder fluxes as shown, for example, on page 31 of the text "Solders and Soldering", H. M. Manko, McGraw-Hill, New York, 1979. However, it has been discovered in accordance with the present invention that when it is attempted to use amines such as those disclosed by Manko as components of cleansing and solder fusing fluids for high temperature automated solder manufacturing processes, such as those used in the manufacture of printing circuits, that unsatisfactory results are obtained. For example, when it is attempted to use amines of this nature in soldering processes operated at temperatures of more than about 100.degree. C. such as temperatures of about 110.degree. to about 250.degree. C., excessive fuming will occur.